Gunman's manifesto describe his actions

BATON ROUGE - The man who killed three Louisiana law enforcement officers purportedly described his actions as a "necessary evil" in a self-described manifesto that an Ohio man says was emailed to him by the gunman less than an hour before the shootings.

The three-page handwritten letter was signed by "Cosmo" - an alias used by Baton Rouge gunman Gavin Long. Photographs of it were attached to an email sent from an address that Long used.

In the manifesto, Long said he expected people who knew him wouldn't believe he would commit "such horrendous acts of violence." But he wrote that he viewed his actions as necessary to "create substantial change within America's police force and judicial system."

The Associated Press obtained a copy of the letter from Yarima Karama, the Ohio man who said he didn't know Long personally, but received several emails from him after Long began commenting on Karama's YouTube videos in March.

Karama has described himself as a hip-hop artist and community activist.